Typically, a distance measuring apparatus comprises a laser for emitting a laser beam to a measuring target, a laser driving circuit for driving the laser, a compensation detector for detecting the timing at which the laser emits the laser beam, and a ranging detector for detecting the laser beam reflected by the measuring target.
The target distance from the laser to the measuring target is calculated based on the emission time corresponding to the time at which the laser beam emitted from the laser is incident on the compensation detector and the incidence time at which the laser beam reflected by the measuring target is incident on the ranging detector. In other words, the target distance is calculated by subtracting the emission time from the incidence time and multiplying one half of the difference with the light velocity.
There is a known distance measuring apparatus which calculates a measurement time period by utilizing the phenomenon that a signal from the compensation detector is output at the same timing as a reference timing. To be more specific, the distance measuring apparatus calculates the measurement time period by causing a distance measuring circuit, which is for measuring an incidence time, to measure a timing at which that signal is output by means of an amplifier for signal detection.
According to the research by the inventor, however, the distance measuring apparatus mentioned above may not be able to correct an error that is due to the delay time of the amplifier used for detection of the signal supplied from the compensation detector. Hence, it may be that the distance measuring apparatus cannot necessarily correct a measurement time period involving errors of a plurality of circuits related to distance measurement.